Endoscopes have long been widely used in medical procedures of directly visualizing the interior of a canal or body cavity. A recent improvement on the endoscope is the video endoscope, wherein fiber optics permit the endoscopic view to be displayed on a video monitor. Video endoscopy provides a number of advantages over traditional endoscopy, including permitting more than one person at a time to observe the endoscopic view, permitting the physician to assume a more comfortable viewing angle, and permitting a videotape record to be made of the endoscopic procedure.
Similarly, modern fluoroscopic technology presents advances over conventional radiography. In conventional radiography, X-rays are projected through a patient onto a photographic film which, when processed, will provide a fixed image of the patient's internal structure. In fluoroscopy, the X-ray sensitive photographic film is replaced by a fluorescent screen which, when subjected to X-radiation, produces a direct image of the object under investigation. Because the image on the fluorescent screen is usually so faint that it difficult to visualize with the unaided eye, the screen image is usually photographed with a sensitive video camera. The video signal is then processed to increase the brightness of the image, and the image is displayed on a video monitor for viewing by the physician. Fluoroscopy affords two primary advantages over conventional radiography: first the image produced is direct, so there is no need for photographic processing; and second, the image is viewed in "real time", rather than as a still photograph or series of still photographs, and can thus show movement.
Surgical modalities are well known wherein video endoscopy is used in conjunction with dye-injection studies under fluoroscopy at various times during the procedure. Examples of such procedures include endoscopic management of biliary tract obstruction and endoscopic sphincterotomy. In these procedures, the physician uses an endoscope to maneuver a catheter down the esophagus, through the stomach, and into position within either the bile duct or pancreatic duct. The endoscopic view is projected on a first video monitor. A quantity of radiographically opaque dye is then injected through the catheter retrograde into the selected duct. Subsequently, the duct is viewed fluoroscopically on a second video monitor, and the X-rays illuminate the dye to reveal obstructions in the biliary system. If the dye does not properly fill the duct, the catheter may have to be repositioned under endoscopic supervision to permit further infusion of dye. When further dye has been infused, the physician again views the duct fluoroscopically. After the procedure has been completed within the first duct, the physician uses the endoscope to reposition the catheter within the other of the bile or pancreatic duct, and the dye injection procedure is repeated. The physician then switches back to the fluoroscopic view to visualize the second duct. Depending upon the success of the initial dye injection into the second duct, the physician may again have to switch to the endoscope to reposition the catheter within the second duct, and then switch back to the fluoroscope to view the duct.
During steps when the physician is using the endoscope rather than the fluoroscope, fluoroscopy may inadvertently continue while the physician's attention is occupied with the endoscopic procedure. The patient and attending medical personnel are thus exposed unnecessarily to excessive dosages of X-rays during those periods when the physician is not actually viewing the fluoroscope. Thus, there is a need to provide a means for avoiding this accidental overexposure of the patient and attending medical personnel to X-rays during periods when the fluoroscope is not actually being used by the physician.